<p>This paper examines the factors that affect the Darveaux model in predicting the fatigue life of BGA solder joints subjected to thermal cycling loads in microsystem packaging structures. Finite element simulations were performed to quantitatively evaluate the impacts of three key parameters on the Darveaux model’s fatigue life prediction accuracy. These parameters include the crack propagation coefficients, the incremental strain energy density, and the fracture characteristic length. A global sensitivity analysis framework based on Monte Carlo sampling was then employed. This approach systematically quantified the sensitivity of fatigue life predictions to material parameters in the Darveaux model under varying fracture characteristic lengths. The findings of this study provide critical insights for the accurate application of the Darveaux model in predicting fatigue life of BGA solder joints under thermal cycling loads.</p>